Field
The invention generally relates to medical devices and procedures pertaining to heart valve repair and prosthetic heart valves. More specifically, the invention relates to repair and/or replacement of heart valves that have malformations or dysfunctions. Embodiments of the invention relate to devices and methods for reshaping or resizing the native mitral valve, further treatments for reducing residual leakage at the mitral valve annulus, and replacement of the functionality of the mitral valve with a prosthetic heart valve, for example, when leakage persists.
Description of Related Art
Referring first generally to FIGS. 1 and 2, the mitral valve controls the flow of blood between the left atrium and the left ventricle of the human heart. After the left atrium receives oxygenated blood from the lungs via the pulmonary veins, the mitral valve permits the flow of the oxygenated blood from the left atrium into the left ventricle. When the left ventricle contracts, the oxygenated blood held in the left ventricle is delivered through the aortic valve and the aorta to the rest of the body. Meanwhile, the mitral valve closes during ventricular contraction, to prevent the flow of blood back into the left atrium.
The mitral valve includes an anterior leaflet and a posterior leaflet. When the left ventricle contracts, the anterior and posterior leaflets come together and the blood pressure in the left ventricle increases substantially to urge the mitral valve closed. Due to the large pressure differential between the left ventricle and the left atrium during ventricular contraction, a possibility of prolapse, or eversion of the leaflets of the mitral valve back into the atrium, arises. To prevent this, a series of chordae tendineae connect the mitral valve to the papillary muscles along opposing walls of the left ventricle. The chordae tendineae are schematically illustrated in both the heart cross-section of FIG. 1 and the top view of the mitral valve in FIG. 2. Just before and during ventricular contraction, the papillary muscles also contract and maintain tension in the chordae tendineae, to hold the leaflets of the mitral valve in the closed position and preventing them from turning inside-out and back into the atrium, thereby also preventing backflow of the oxygenated blood into the atrium.
A general shape of the mitral valve and its leaflets as seen from the left atrium is illustrated in FIG. 2. Complications of the mitral valve can potentially cause fatal heart failure. One form of valvular heart disease is mitral valve leak, also known as mitral regurgitation, characterized by the abnormal leaking of blood from the left ventricle back into the left atrium through the mitral valve.
Mitral regurgitation is a common problem, and various options to reduce or prevent mitral regurgitation that can be more easily tolerated or handled by a body of a patient have been researched.
One repair solution for a patient exhibiting mitral regurgitation or other mitral valve leakage employs a catheter procedure, where a free edge of the anterior leaflet is attached to a free edge of the posterior leaflet. The idea for this procedure was promoted by Dr. Ottavio Alfieri, who described seeing a patient who had a congenital anomaly where the anterior leaflet edge was fused to the posterior leaflet edge, and surmised that that could potentially provide a good solution to mitral regurgitation. Dr. Alfieri performed many procedures where the mitral annulus was repaired by reduction using an annuloplasty ring to reshape the native mitral valve annulus to be smaller and/or more circular or otherwise consistent, and then controlling residual leakage by an approximation and attachment of the anterior leaflet edge to the posterior leaflet edge at a desired arrangement. Performance of many leaky mitral valves can be repaired and improved by what has become known as the Alfieri procedure, utilizing a combination of annuloplasty to reduce the diameter of the mitral annulus and leaflet edge approximation.
The Alfieri procedure has led to other variations of catheter-based procedures to attach the edges of the anterior and posterior leaflets to control mitral regurgitation. In one procedure, under echocardiographic and fluoroscopic guidance, catheters are used to introduce a clip at the mitral annulus that fastens the free edge of the anterior leaflet to the free edge of the posterior leaflet. The clip and a delivery system are typically introduced in the patient's femoral vein and passed into the right side of the heart. A transseptal puncture is then carried out in the patient's heart, and the clip is advanced into the left atrium and then the left ventricle. The edges of the leaflets are then fastened together with the clip, and the delivery system is withdrawn. In other variations of the procedure, the clip and delivery system can instead be introduced into the patient's heart from one of various other access points or positions on the patient's body.
Most patients have one clip applied during such a procedure, but if the leak is severe and/or the leaflets are highly distracted, additional clips can also be applied. The clinical results have been gratifying. Many patients have exhibited a major reduction in leakage and are symptomatically much improved when compared to before undergoing the procedure.
Another option to further reduce the mitral leakage would be to combine or to supplement one of the above annuloplasty procedures with an edge to edge leaflet plication procedure to further strengthen the bond or attachment between the native mitral leaflets.